1. Field of the Invention
The present invention relates to a cast iron slide member, and particularly to a slide member for use under a high surface pressure.
2. Description of the Prior Art
A cast iron cam shaft for an internal combustion engine is conventionally known as such a slide member. The entire outer peripheral area, on the camshaft can be a slide portion, or a half of the outer peripheral area, including a nose portion, can be the slide portion. In either case, the entire slide portion of this structure is chilled.
When such a cam shaft is used under a high surface pressure, pitting and scuffing resistances of the nose portion becomes a problem.
In order to improve the pitting and scuffing resistances of this sliding portion, it is required that the chilled structure of the nose portion is a uniform fine structure having a large amount of precipitated free cementite. Such a structure has a high hardness. The hardness of the base structure is not reduced by a strain relief annealing conducted at a thermally treating temperature of 600.degree. C. after casting.